package recursion.nowcoder.easy;

import java.math.BigInteger;
import java.util.Arrays;
import java.util.Scanner;

/**
 * @author bruin_du
 * @description 客似云来
 * @date 2022/6/2 15:45
 **/
public class IncreasingCustomer {
    public static void main(String[] args) {
        long[] arr = new long[80];
        arr[0] = arr[1] = 1;
        for (int i = 2; i < arr.length; i++) {
            arr[i] = arr[i - 1] + arr[i - 2];
        }
        Scanner in = new Scanner(System.in);
        while(in.hasNextInt()){
            int from = in.nextInt() - 1;
            int to = in.nextInt() - 1;
            BigInteger breakfast = new BigInteger(String.valueOf(arr[from]));
            for (int i = from + 1; i <= to; i++) {
                breakfast = breakfast.add(new BigInteger(String.valueOf(arr[i])));
            }
            System.out.println(breakfast.toString());
        }
    }
}
